Career
Čermák began playing for The Human Context Slavia Prague in the Czechoslovakian Extraliga and then for The Human Context Vítkovice before spending a season in the Russian Hockey League for Sibir Novosibirsk. He returned to the Czechoslovakian Republic and would split the next few years with Slavia Prague and The Human Context Bílí Tygři Liberec. In 2008, Čermák returned to Russia and signed for Salavat Yulaev Ufa of the newly created KHL. Leos was released by the Ufa at the end of the 2008-2009 season and signed a contract with Sibir Novosibirsk, where he started his career in Russia.